The invention concerns a teeth-cleaning device with a handle and at least one interdental treatment element in the form of, for example, a soft brush and/or a hard brush and/or a toothpick, which treatment element is provided on the handle protruding transversely to its longitudinal extension, in a detachable and exchangeable manner, and in the operating position is locked by means of a lock which can be fastened in a locked position, wherein the treatment element or one retaining device associated with it in the operating position passes through the hole which extends transversely to the handle and the treatment element or its retaining device in the case of an open lock, when it exposes the cross-section of the hole, can be inserted into the hole and, furthermore, wherein in the closed position the lock overlaps the hole and prevents the removal of the treatment element.
Such a teeth-cleaning device is known from EP-O 311 937 B1. In this case the treatment element is a cylindrical or tapered hard brush, where the bristles are held by a twisted wire which can be anchored as a retaining element in a hole of the handle with a lock. In this case the lock is a slide which can be displaced transversely to the central axis of the treatment element and coaxially to the end of the handle, the lock having an opening on the face, with which a retaining plate of the treatment element can be engaged in the locked position. At the same time, the slide is constructed as a sleeve and for the purpose of replacing the treatment element it can be pushed in the direction of the handle away from its end. Therefore the pushing movement to open this lock is against that direction with which the handle and the treatment element are introduced into the mouth and possibly in the region of the molar teeth, so that there will be a danger that during the insertion the sleeve can be moved unintentionally into the open position. Therefore during the cleaning of the interdental region, i.e. the region between two teeth, which is often not simple to clean, the lock can open and the treatment element can become detached from its retaining device. This can even result in injuries in the oral cavity.
From U.S. Pat. No. 4,780,923 a teeth-cleaning device of the type mentioned in the introduction is known, wherein a pivoting flap is used as a lock, the pivot axis of which is provided on the outermost end of the handle on the face in such a manner that the hole for retaining the treatment element is oriented more towards the center of the handle. At the same time, the pivot axis is oriented transversely or perpendicularly to the extension of the handle and to the extension of the central axis of the treatment element. In the closed position, this flap-shaped lock is supposed to be locked relative to the end of the handle by virtue of the design of its cross-section, while laterally protruding flanges are provided to seize the opening and closing movements.
In this case too, there is the danger that, for example, if one slips during the cleaning of the interdental region, especially of the molar teeth, these actuating flanges will come to rest against the edge of the teeth or the like in such a manner that the lock could open unintentionally. Moreover, the manufacture of the parts which fit each other and interlock with each other and their joining with a transversely extending axis is relatively complicated. In addition, when closing this pivoting lock the retaining wire of the brush-shaped treatment element is bent over in the same direction in which this lock is folded for the purpose of closing, so that the lock is also under the tension of this retaining device of the treatment element, the tension acting in the direction of opening.
From EP-A-0 537 663 A1 a teeth-cleaning device of the same kind is known, wherein as treatment element an approximately cylindrical brush with a central retaining wire is provided, while the retaining wire is anchored as a retaining device in a hole of the handle. In the initial position, this wire passes through a hole and protrudes past the handle on that side which is averted from the brush. As a lock a slide is used which can be displaced transversely to this wire and coaxially towards the end of the handle, which slide with a stop is first at a greater distance to the face of the handle and then is pushed onto this handle. At the same time its rearward portion acts on the protruding portion of the retaining wire and bends it while being pushed on. Although by virtue of this the direction of pushing approximately agrees with the load during the introduction of the teeth-cleaning device into the mouth, it is, however, not ruled out that during the cleaning movements the lock is pushed inadvertently back again into the open position.
From DE-A-42 23 196 A1 a brush holder for a toothbrush is known, which also has a lock, which during the locking process is moved perpendicularly to the longitudinal axis of the treatment element. At the same time, the lock is provided pivotably on a recess, into which a retaining wire for the bristles can be inserted. In the region of this recess this retaining wire is deformed and is axially secured by the lock by pivoting it into the closed position. Apart from the elaborate construction of the actual brush holder and the mounting of this lock, with an actuating end it faces the actual brush holder so that it could be opened again. Thus an unintentional opening cannot be ruled out.